First of all, you don't need a new server to run AC. I would stay with the server you have. Also, I don't care if Win 8 Pro were one dollar, I would go with Win 7 Pro. And, if your "IT guy" charged you $2500.00 to set up your server/network, that is outrageous. Check the versions on the i5 and i7. If same price, why not, but an i5 is fine. Can't go wrong with large hard drives, but I have used 80GBs in a RAID 1 for five years. That's a lot of space. Moving your database isn't that hard. Anyone can help. But if the tech support wants to do it, that's fine.
Geez: Even if your tech support worked ten hours, far more than necessary for a small network, then he charged $250/hr which is ridiculous. Most good IT techs charge from $90.00 to $120.00. In that situation, I would have contracted for one price up front. Working with computers always takes longer than predicted.
Can you tell us the server machine you have now. Hard to imagine that a Dell Optiplex will be a better machine.
